From: Matt S Trout <mst@shadowcat.co.uk>
Date: Wed, 27 Jun 2007 05:59:28 +0000 (+0000)
Subject: seems to have vanished
X-Git-Tag: 0.001000~1
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=c0f47301771431ee488220ae667425f2c741e71b;p=p5sagit%2FDevel-BeginLift.git

seems to have vanished
---

diff --git a/BeginLift.xs b/BeginLift.xs
new file mode 100644
index 0000000..59cd790
--- /dev/null
+++ b/BeginLift.xs
@@ -0,0 +1,122 @@
+#define PERL_CORE
+#define PERL_NO_GET_CONTEXT
+#include "EXTERN.h"
+#include "perl.h"
+#include "XSUB.h"
+#include <stdio.h>
+#include <string.h>
+
+/* lifted from op.c */
+
+#define LINKLIST(o) ((o)->op_next ? (o)->op_next : linklist((OP*)o))
+
+/* pointer to old PL_check entersub entry to be populated in init */
+
+STATIC OP *(*dbl_old_ck_entersub)(pTHX_ OP *op);
+
+/* replacement PL_check entersub entry */
+
+STATIC OP *dbl_ck_entersub(pTHX_ OP *o) {
+  OP *kid;
+  OP *last;
+  OP *curop;
+  HV *stash;
+  I32 type = o->op_type;
+  SV *sv;
+  SV** stack_save;
+  HV* to_lift;
+  SV** to_lift_pack_ref;
+  HV* to_lift_pack_hash;
+  SV** to_lift_flag_ref;
+
+  o = dbl_old_ck_entersub(aTHX_ o); /* let the original do its job */
+
+  kid = cUNOPo->op_first;
+
+  if (kid->op_type != OP_NULL) /* pushmark for method call ... */
+    return o;
+
+  last = kLISTOP->op_last;
+
+  if (last->op_type != OP_NULL) /* not what we expected */
+    return o;
+
+  kid = cUNOPx(last)->op_first;
+
+  if (kid->op_type != OP_GV) /* not a GV so ignore */
+    return o;
+
+  stash = GvSTASH(kGVOP_gv);
+
+  /* printf("Calling GV %s -> %s\n",
+    HvNAME(stash), GvNAME(kGVOP_gv)); */
+
+  to_lift = get_hv("Devel::BeginLift::lift", FALSE);
+
+  if (!to_lift)
+    return o;
+
+  to_lift_pack_ref = hv_fetch(to_lift, HvNAME(stash), strlen(HvNAME(stash)),
+                               FALSE);
+
+  if (!to_lift_pack_ref || !SvROK(*to_lift_pack_ref))
+    return o; /* not a hashref */
+
+  to_lift_pack_hash = (HV*) SvRV(*to_lift_pack_ref);
+
+  to_lift_flag_ref = hv_fetch(to_lift_pack_hash, GvNAME(kGVOP_gv),
+                                strlen(GvNAME(kGVOP_gv)), FALSE);
+
+  if (!to_lift_flag_ref || !SvTRUE(*to_lift_flag_ref))
+    return o;
+
+  /* shamelessly lifted from fold_constants in op.c */
+
+  stack_save = PL_stack_sp;
+  curop = LINKLIST(o);
+  o->op_next = 0;
+  PL_op = curop;
+  CALLRUNOPS(aTHX);
+
+  if (PL_stack_sp > stack_save) { /* sub returned something */
+    sv = *(PL_stack_sp--);
+    if (o->op_targ && sv == PAD_SV(o->op_targ)) /* grab pad temp? */
+      pad_swipe(o->op_targ,  FALSE);
+    else if (SvTEMP(sv)) {      /* grab mortal temp? */
+      (void)SvREFCNT_inc(sv);
+      SvTEMP_off(sv);
+    }
+    op_free(o);
+    if (type == OP_RV2GV)
+      return newGVOP(OP_GV, 0, (GV*)sv);
+    return newSVOP(OP_CONST, 0, sv);
+  } else {
+    /* this bit not lifted, handles the 'sub doesn't return stuff' case
+       which fold_constants can ignore */
+    op_free(o);
+    return newOP(OP_NULL, 0);
+  }
+}
+
+static int initialized = 0;
+
+MODULE = Devel::BeginLift  PACKAGE = Devel::BeginLift
+
+PROTOTYPES: DISABLE
+
+void
+setup()
+  CODE:
+  if (!initialized++) {
+    dbl_old_ck_entersub = PL_check[OP_ENTERSUB];
+    PL_check[OP_ENTERSUB] = dbl_ck_entersub;
+  }
+
+void
+teardown()
+  CODE:
+  /* ensure we only uninit when number of teardown calls matches 
+     number of setup calls */
+  if (initialized && !--initialized) {
+    PL_check[OP_ENTERSUB] = dbl_old_ck_entersub;
+  }